Muscle forces acting on the greater trochanter lead to a dorsal warping of the apophyseal growth plate.

The apophyseal growth plate of the greater trochanter, unlike most other growth plates of the human body, exhibits a curved morphology that results in a divergent pattern resembling an open crocodile mouth on plain antero-posterior radiographs. To quantify the angular alignment of the growth plate and to draw conclusions about the function of the muscles surrounding it, we analyzed 57 MRI images of 51 children and adolescents aged 3-17 years and of six adults aged 18-52 years. We measured the angulation of the plate relative to the horizontal plane (AY angle) and the trajectories of the muscles attaching to the greater trochanter of the proximal femur. From anterior to posterior, the AY angle shows a decrease of 33.44°. In the anterior third, the cartilage is angled at a mean of 51.64°, and in the posterior third, the mean angulation is 18.6°. This indicates that the cartilage in the anterior region of the greater trochanteric apophysis is subject to more vertically oriented force vectors compared to the posterior region, as the growth plates align perpendicular to the force vectors acting on them. Combining the measured muscle trajectories with the physiological cross-sectional areas (PCSA) available from the literature revealed that, in addition to the known internal and external lateral traction ligament systems, a third, dorsally located traction ligament system exists that may be responsible for the dorsal deformation of the AY angle.

Automated assessment of cardiac pathologies on cardiac MRI using T1-mapping and late gadolinium phase sensitive inversion recovery sequences with deep learning.

BACKGROUND: A deep learning (DL) model that automatically detects cardiac pathologies on cardiac MRI may help streamline the diagnostic workflow. To develop a DL model to detect cardiac pathologies on cardiac MRI T1-mapping and late gadolinium phase sensitive inversion recovery (PSIR) sequences were used. METHODS: Subjects in this study were either diagnosed with cardiac pathology (n = 137) including acute and chronic myocardial infarction, myocarditis, dilated cardiomyopathy, and hypertrophic cardiomyopathy or classified as normal (n = 63). Cardiac MR imaging included T1-mapping and PSIR sequences. Subjects were split 65/15/20% for training, validation, and hold-out testing. The DL models were based on an ImageNet pretrained DenseNet-161 and implemented using PyTorch and fastai. Data augmentation with random rotation and mixup was applied. Categorical cross entropy was used as the loss function with a cyclic learning rate (1e-3). DL models for both sequences were developed separately using similar training parameters. The final model was chosen based on its performance on the validation set. Gradient-weighted class activation maps (Grad-CAMs) visualized the decision-making process of the DL model. RESULTS: The DL model achieved a sensitivity, specificity, and accuracy of 100%, 38%, and 88% on PSIR images and 78%, 54%, and 70% on T1-mapping images. Grad-CAMs demonstrated that the DL model focused its attention on myocardium and cardiac pathology when evaluating MR images. CONCLUSIONS: The developed DL models were able to reliably detect cardiac pathologies on cardiac MR images. The diagnostic performance of T1 mapping alone is particularly of note since it does not require a contrast agent and can be acquired quickly.

Impact of Dynamic Contrast Enhanced and Diffusion-Weighted MR Imaging on Detection of Early Local Recurrence of Soft Tissue Sarcoma.

BACKGROUND: Diagnosis of residual or recurrent tumor in soft-tissue sarcomas (STS) is a differential diagnostic challenge since post-therapeutic changes impede diagnosis. PURPOSE: To evaluate the diagnostic accuracy of quantitative dynamic contrast enhanced (DCE)-MRI and diffusion-weighted imaging (DWI) to detect local recurrence of STS of the limb. STUDY TYPE: Prospective. POPULATION: A totalof 64 consecutive patients with primary STS of the limbs were prospectively included 3-6 months after surgery between January 2016 and July 2021. FIELD STRENGTH/SEQUENCE: A 1.5 T; axial DWI echo-planar imaging sequences and DCE-MRI using a 3D T1-weighted spoiled gradient-echo sequence. ASSESSMENT: The quantitative DCE-MRI parameters relative plasma flow (rPF) and relative mean transit time (rMTT) were calculated and ADC mapping was used to quantify diffusion restriction. Regions of interest of tumor growth and postoperative changes were drawn in consensus by two experts for diffusion and perfusion analysis. An additional morphological assessment was done by three independent and blinded radiologists. STATISTICAL TEST: Unpaired t-test, ROC-analysis, and a logistic regression model were applied. Interobserver reliability was calculated using Fleiss kappa statistics. A P value of 0.05 was considered statistically significant. RESULTS: A total of 11 patients turned out to have local recurrence. rPF was significantly higher in cases of local recurrence when compared to cases without local recurrence (61.1-4.5) while rMTT was slightly and significantly lower in local recurrence. ROC-analysis showed an area under the curve (AUC) of 0.95 (SEM ± 0.05) for rPF while a three-factor multivariate logistic regression model showed a high diagnostic accuracy of rPF (R2  = 0.71). Compared with morphological assessment, rPF had a distinct higher specificity and true positive value in detection of LR. DATA CONCLUSION: DCE-MRI is a promising additional method to differentiate local recurrence from benign postoperative changes in STS of the limb. Especially specificity in detection of LR is increased compared to morphological assessment. EVIDENCE LEVEL: 1 TECHNICAL EFFICACY: Stage 2.

Transjugular intrahepatic portosystemic shunt creation (TIPS) in the angio-CT-a hybrid intervention with image fusion.

OBJECTIVE: For transjugular intrahepatic portosystemic shunt (TIPS) creation, ultrasound guidance for portal vein puncture is strongly recommended. However, outside regular hours of service, a skilled sonographer might be lacking. Hybrid intervention suites combine CT imaging with conventional angiography allowing to project 3D information into the conventional 2D imaging and further CT-fluoroscopic puncture of the portal vein. The purpose of this study was to assess whether TIPS using angio-CT facilitates the procedure for a single interventional radiologist. METHODS: All TIPS procedures from 2021 and 2022 which took place outside regular working hours were included (n = 20). Ten TIPS procedures were performed with just fluoroscopy guidance and ten procedures using angio-CT. For the angio-CT TIPS, a contrast-enhanced CT was performed on the angiography table. From the CT, a 3D volume was created using virtual rendering technique (VRT). The VRT was blended with the conventional angiography image onto the live monitor and used as guidance for the TIPS needle. Fluoroscopy time, area dose product, and interventional time were assessed. RESULTS: Hybrid intervention with angio-CT did lead to a significantly shorter fluoroscopy time and interventional time (p = 0.034 for both). Mean radiation exposure was significantly reduced, too (p = 0.04). Furthermore, the mortality rate was lower in patients who underwent the hybrid TIPS (0% vs 33%). CONCLUSION: TIPS procedure in angio-CT performed by only one interventional radiologist is quicker and reduces radiation exposure for the interventionalist compared to mere fluoroscopy guidance. The results further indicate increased safety using angio-CT. CLINICAL RELEVANCE STATEMENT: This study aimed to evaluate the feasibility of using angio-CT in TIPS procedures during non-standard working hours. Results indicated that the use of angio-CT significantly reduced fluoroscopy time, interventional time, and radiation exposure, while also leading to improved patient outcomes. KEY POINTS: • Image guiding such as ultrasound is recommended for transjugular intrahepatic portosystemic shunt creation but might be not available for emergency cases outside of regular working hours. • Transjugular intrahepatic portosystemic shunt creation using an angio-CT with image fusion is feasible for only one physician under emergency settings and results in lower radiation exposure and faster procedures. • Transjugular intrahepatic portosystemic shunt creation using an angio-CT with image fusion seems to be safer than using mere fluoroscopy guidance.

Efficacy of ultrasound assisted catheter-directed thrombolysis compared to catheter-directed thrombolysis in vitro.

BACKGROUND: Catheter-directed thrombolysis (CDT) is an effective and safe endovascular method used in critical limb ischemia and many other thromboembolic events. Ultrasound-assisted catheter-directed thrombolysis (US-CDT) is an emerging technique considered to accelerate thrombolysis and therefore is supposed to improve outcome. PURPOSE: To evaluate the efficacy of US-CDT in comparison to standard CDT in vitro. MATERIAL AND METHODS: A total of 69 sets of human venous blood were evaluated, each comprising a tube just treated with CDT, a tube treated with US-CDT, and a control tube. All tubes were kept under physiological conditions. Except for the controls, in all tubes 5 mg of tissue-type plasminogen activator was administered over the predetermined treatment interval. Thrombus mass was weighted at the end of the lysis intervals at 6 h or 24 h, respectively. RESULTS: CDT led to a mean thrombus reduction of 32% and ultrasound-assisted lysis led to a mean thrombus reduction of 41% (P < 0.001 for both). Thrombus reduction was significantly higher after US-CDT compared to CDT (P = 0.001). The better efficacy of US-CDT was mostly already apparent at early phases during thrombolysis and did further mildly increase over time (r = 0.24; P = 0.047). CONCLUSION: In vitro US-CDT is significantly superior to standard CDT; this effect is apparent at an early timepoint of lysis and slightly further increases over time.

[Imaging of intrahepatic cholangiocarcinoma : Reliable diagnosis according to the new S3 guideline]. / Bildgebung beim intrahepatischen Cholangiokarzinom : Richtige Diagnostik nach der neuen S3-Leitlinie.

The S3 guideline on hepatocellular carcinoma has been expanded to include malignant biliary carcinoma (synonym cholangiocarcinoma [CCA]). Magnetic resonance imaging (MRI) with additional magnetic resonance cholangiopancreatography (MRCP) is the imaging modality of choice to evaluate local findings. Use of gadolinium ethoxybenzyl diethylenetriamine penta-acetic acid (Gd-EOB-DTPA)-based contrast agent increases its diagnostic value. Histologic confirmation is always required when diagnosing intrahepatic CCA (iCCA) because using imaging alone there is a risk of confusion with HCC subtypes.

Multiscale X-ray phase contrast imaging of human cartilage for investigating osteoarthritis formation.

BACKGROUND: The evolution of cartilage degeneration is still not fully understood, partly due to its thinness, low radio-opacity and therefore lack of adequately resolving imaging techniques. X-ray phase-contrast imaging (X-PCI) offers increased sensitivity with respect to standard radiography and CT allowing an enhanced visibility of adjoining, low density structures with an almost histological image resolution. This study examined the feasibility of X-PCI for high-resolution (sub-) micrometer analysis of different stages in tissue degeneration of human cartilage samples and compare it to histology and transmission electron microscopy. METHODS: Ten 10%-formalin preserved healthy and moderately degenerated osteochondral samples, post-mortem extracted from human knee joints, were examined using four different X-PCI tomographic set-ups using synchrotron radiation the European Synchrotron Radiation Facility (France) and the Swiss Light Source (Switzerland). Volumetric datasets were acquired with voxel sizes between 0.7 × 0.7 × 0.7 and 0.1 × 0.1 × 0.1 µm3. Data were reconstructed by a filtered back-projection algorithm, post-processed by ImageJ, the WEKA machine learning pixel classification tool and VGStudio max. For correlation, osteochondral samples were processed for histology and transmission electron microscopy. RESULTS: X-PCI provides a three-dimensional visualization of healthy and moderately degenerated cartilage samples down to a (sub-)cellular level with good correlation to histologic and transmission electron microscopy images. X-PCI is able to resolve the three layers and the architectural organization of cartilage including changes in chondrocyte cell morphology, chondrocyte subgroup distribution and (re-)organization as well as its subtle matrix structures. CONCLUSIONS: X-PCI captures comprehensive cartilage tissue transformation in its environment and might serve as a tissue-preserving, staining-free and volumetric virtual histology tool for examining and chronicling cartilage behavior in basic research/laboratory experiments of cartilage disease evolution.

[Comparison of radiation exposure in common hepatic interventions : A retrospective analysis of DeGIR registry data]. / Strahlenexposition bei häufigen interventionellen Eingriffen der Leber im Vergleich : Retrospektive Analyse von DeGIR-Registerdaten.

BACKGROUND: Transcatheter arterial chemoembolization (TACE) and biliary interventions are common procedures. OBJECTIVES: In this retrospective study, the radiation exposure of patients undergoing hepatic intervention will be analyzed and compared depending on the type and objective of the intervention. MATERIALS AND METHODS: This is an analysis of 7003 data sets of performed TACEs and biliary interventions from the DeGIR registry for the years 2016, 2017, and 2018. The dose area product (DAP), fluoroscopy time (FT), type of intervention, and anatomically defined target were recorded. RESULTS: Data with documented radiation doses were available for 4985 TACEs and for 2018 biliary interventions. For biliary interventions the median DAP was 2594 (interquartile range [IQR] = 1174-5858) cGycm2. For TACE, the median DAP was 11,632 [IQR = 5530-22,800] cGycm2 and significantly higher compared to biliary interventions (p < 0.0001). Biliary interventions with the highest DAP take place at the common hepatic duct; procedures with the longest FT were registered at the hepatic duct bifurcation. CONCLUSIONS: The individual radiation exposure during liver interventions is less dependent of the complexity of the procedure or the fluoroscopy time, but rather on the type of intervention and the anatomic target. The presented data can help to approximately estimate the radiation exposure in advance when planning an intervention.

Quantitative Assessment of Degenerative Cartilage and Subchondral Bony Lesions in a Preserved Cadaveric Knee: Propagation-Based Phase-Contrast CT Versus Conventional MRI and CT.

OBJECTIVE: The aim of this study was to quantitatively assess hyaline cartilage and subchondral bone conditions in a fully preserved cadaveric human knee joint using high-resolution x-ray propagation-based phase-contrast imaging (PBI) CT and to compare the performance of the new technique with conventional CT and MRI. MATERIALS AND METHODS: A cadaveric human knee was examined using an x-ray beam of 60 keV, a detector with a 90-mm2 FOV, and a pixel size of 46 × 46 µm2. PBI CT images were reconstructed with both the filtered back projection algorithm and the equally sloped tomography method. Conventional 3-T MRI and CT were also performed. Measurements of cartilage thickness, cartilage lesions, International Cartilage Repair Society scoring, and detection of subchondral bone changes were evaluated. Visual inspection of the specimen akin to arthroscopy was conducted and served as a standard of reference for lesion detection. RESULTS: Loss of cartilage height was visible on PBI CT and MRI. Quantification of cartilage thickness showed a strong correlation between the two modalities. Cartilage lesions appeared darker than the adjacent cartilage on PBI CT. PBI CT showed similar agreement to MRI for depicting cartilage substance defects or lesions compared with the visual inspection. The assessment of subchondral bone cysts showed moderate to strong agreement between PBI CT and CT. CONCLUSION: In contrast to the standard clinical methods of MRI and CT, PBI CT is able to simultaneously depict cartilage and bony changes at high resolution. Though still an experimental technique, PBI CT is a promising high-resolution imaging method to evaluate comprehensive changes of osteoarthritic disease in a clinical setting.

Transient Bone Marrow Edema Syndrome versus Osteonecrosis: Perfusion Patterns at Dynamic Contrast-enhanced MR Imaging with High Temporal Resolution Can Allow Differentiation.

Purpose To prospectively evaluate the perfusion patterns at quantitative dynamic contrast material-enhanced (DCE) magnetic resonance (MR) imaging of transient bone marrow edema syndrome (TBMES) and avascular osteonecrosis. Materials and Methods Institutional review board approval and written informed consent were obtained. Thirty-two patients (21 men, 11 women; mean age, 48 years; 26 hips, 10 knees) underwent conventional MR imaging and a dynamic contrast-enhanced three-dimensional spoiled gradient-echo sequence at 3 T. Parameter maps for mean transit time (MTT) and plasma flow (PF) were evaluated qualitatively and quantitatively. Differences in perfusion patterns were analyzed by using the Fisher exact test. Regions of interest were drawn in areas of high PF and long MTT on each parametric map. Mean, median, standard deviation, minimum, and maximum values were determined. TBMES and osteonecrosis were compared statistically by using the Mann-Whitney U and Wilcoxon signed-rank tests, with a P value of less than .05 considered indicative of a significant difference. Results Nineteen joints with TBMES and 17 joints with osteonecrosis were evaluated. TBMES joints showed a subchondral elongated area of high PF and low MTT that was surrounded by an area of long MTT and low PF. Osteonecrosis joints showed a subchondral area with low or no detectable PF and MTT adjacent to the joint surface, which was surrounded by a rim of high PF and intermediate MTT. Patterns for TBMES and osteonecrosis did not overlap. A significant difference (P < .001) in PF in the immediate subchondral area was found between TBMES and osteonecrosis; in joints with osteonecrosis, this was comparable to background noise, and therefore, could not be quantified. In the circumscribed rim of high PF and intermediate MTT, which was only found in joints with osteonecrosis, mean ± standard deviation PF was 18.9 mL/100 mL per minute ± 11.0 and mean MTT was 213.3 seconds ± 56.8. No significant difference between TBMES and osteonecrosis was found for MTT (P = .09) and PF (P = .75) in the surrounding area. Conclusion Parameter maps derived at dynamic contrast-enhanced MR imaging with high temporal resolution can allow differentiation of osteonecrosis from TBMES in hip and knee joints. © RSNA, 2016 Online supplemental material is available for this article.